This invention relates to a pattern feature extracting device for extracting pattern features from an area having a multiplicity of streaks at least on a fragmentary area thereof. The whole area will herein be referred to as a streaked pattern. A typical streaked pattern is a fingerprint with its background. The fingerprints, as called herein, may be a palm print, a toe print, a soleprint, an actual finger, or a pattern drawn by a skilled technician after a faint fingerprint remain or a latent fingerprint. The device is particularly useful for recognition, namely, discrimination, collation, and/or identification of the fingerprints.
Important pattern features of a fingerprint are those positions and directions of minutiae, such as bifurcation and abrupt endings "ridges," which will be named minutia positions and directions for the time being and will be defined later more exactly with reference to several of nearly twenty figures of the accompanying drawing. When a fingerprint is clearly impressed on a recording medium, such as a card, it is usually possible to extract the minutia positions and directions from such a fingerprint register to a number sufficient for recognition. The number of such minutia positions and directions is, however, generally meger when the fingerprint is one left at a scene of crime as a fingerprint remain or a latent fingerprint, which may be only a part of the fingerprint and be distorted.
K. Millard therefore revealed an improved device of the type specified hereinabove in his report titled "An Automatic Retrieval System for Scene of Crime Fingerprints" in Proceedings of Conference on the Science of Fingerprints, 24-25 September 1974, pages 1-14. Inter-minutia "ridge" counts between each minutia and five nearest minutiae to the right, of the type to be described later with reference to a few of the accompanying drawing figures, are used by Millard as "relationships (links)" besides the minutia positions and directions. The ridge counts are very effective in enhancing the pattern features and raising the accuracy and speed of fingerprint recognition.
It is thus urgently required to improve the information relating to the pattern features to be extracted from a streaked pattern without much complicating the device.